This invention relates to methods for performing a medical procedure, especially a procedure during which it is necessary to adjust the beating of the heart. More particularly, this invention relates to methods and systems of stimulating a nerve in order to modify the beating of a heart to allow a medical procedure to be performed or for blood flow to be controlled.
The current leading cause of death in the United States is coronary artery disease in which the coronary arteries are blocked by atherosclerotic plaques or deposits of fat. The typical treatment to relieve a partially or fully blocked coronary artery is coronary artery bypass graph (CABG) surgery.
CABG surgery, also known as xe2x80x9cheart bypassxe2x80x9d surgery, generally entails using a graph to bypass the coronary obstruction. The procedure is generally lengthy, traumatic and subject to patient risks. Among the risk factors involved is the use of a cardiopulmonary bypass (CPB) circuit, also known as a xe2x80x9cheart-lung machine,xe2x80x9d to pump blood and oxygenate the blood so that the patient""s heart may be stopped during the surgery.
Conventional CABG procedures are typically conducted on a stopped heart while the patient is on a (CPB) circuit. A stopped heart and a CPB circuit enables a surgeon to work in a bloodless, still operative field. However, there are a number of problems associated with CABG procedures performed while on CPB including the initiation of a systemic inflammatory response due to interactions of blood elements with the artificial material surfaces of the CPB circuit and global myocardial ischemia due to cardioplegic cardiac arrest. For these reasons, avoiding the use of CPB or cardioplegic cardiac arrest may help minimize post-operative complications.
One method, as disclosed in U.S. Pat. No. 5,651,378 to inventors Matheny and Taylor and in U.S. Pat. No. 5,913,876 to inventors Taylor et al., for facilitating coronary bypass surgery on a beating heart and thereby avoid the use of CPB and cardioplegic cardiac arrest includes stimulating the vagal nerve electrically in order to temporarily stop or substantially reduce the beating of the heart. This may be followed by pacing the heart to start its beating.
Another method, as disclosed in two published PCT applications, WO 99/09971 and WO 99/09973, both to inventor Puskas, involves stopping the beating of the heart during coronary bypass surgery using electrical stimulation of the vagal nerve in combination with administration of drugs. Another method, as disclosed in U.S. Pat. No. 6,060,454 to inventor Duhaylongsod, involves stopping the beating of the heart during coronary bypass surgery via the local delivery of drugs to the heart.
Although it is desirable to stop the heart for a period of time in order to allow the surgeon to accomplish a required task without interference from heart movement, i.e. a motionless operative field, it is undesirable to have the heart stopped for too long a period of time since the body needs, among other things, a constant supply of oxygen. In fact, it is particularly important to maintain sufficient blood flow, and therefore oxygen flow, to the brain. Stopping the heart for prolonged periods of time may cause damage to the patient.
It would be desirable therefore to provide a method for controllably stopping or slowing the heart intermittently for diagnostic purposes.
Additionally, it would be desirable to provide a method for controllably stopping or slowing the heart intermittently for therapeutic purposes.
Additionally, it would be desirable to provide a method for controllably stopping or slowing the heart intermittently in order to control blood flow.
Additionally, it would be desirable to provide a method for controllably stopping or slowing the heart intermittently in order to perform a medical procedure on the heart or another organ.
One aspect of the present invention provides a method of performing a medical procedure. The method includes stimulating a nerve to adjust the beating of a heart to a first condition. A medical procedure is then performed the medical procedure on an organ. Stimulation of the nerve is then reduced to adjust the beating of a heart to a second condition. The nerve is then stimulated a subsequent time in order to re-adjust the beating of the heart to the first condition and then the medical procedure is continued.
The nerve may be stimulated using transvascular stimulation. The stimulation may be stopped to achieve the second condition. The first condition may be a stopped or a slowed condition. The second condition may be a beating condition. The heart may also be stimulated to adjust the beating of the heart to the second condition. The heart may be stimulated by pacing.
Drugs, such as a beta-blocker, a cholinergic agent, a cholinesterase inhibitor, a calcium channel blocker, a sodium channel blocker, a potassium channel agent, adenosine, an adenosine receptor agonist, an adenosine deaminase inhibitor, dipyridamole, a monoamine oxidase inhibitor, digoxin, digitalis, lignocaine, a bradykinin agent, a serotoninergic agonist, an antiarrythmic agent, a cardiac glycoside, a local anesthetic, atropine, a calcium solution, an agent that promotes heart rate, an agent that promotes heart contractions, dopamine, a catecholamine, an inotrope glucagon, a hormone, forskolin, epinephrine, norepinephrine, thyroid hormone, a phosphodiesterase inhibitor, prostacyclin, prostaglandin and a methylxanthine, may be delivered during the medical procedure. These drugs may be naturally occurring or chemically synthesized.
The nerve being stimulated may be vagus nerve fibers, hypoglossal nerve fibers, phrenic nerve fibers, parasympathetic nerve fibers, and sympathetic nerve fibers, a vagal nerve, a carotid sinus nerve, a fat pad. The organ may be the heart.
The medical procedure may be surgical procedures, non-surgical procedures, endoscopic procedures, fluoroscopic procedures, stent delivery procedures, aortic aneurysm repairs, cranial aneurysm repairs, delivery of drugs, delivery of biological agents, cardiac surgery with cardiopulmonary bypass circuits, cardiac surgery without cardiopulmonary bypass circuits, brain surgery, cardiograms, heart valve repair, heart valve replacement, MAZE procedures, transmyocardial revascularization, CABG procedures, beating heart surgery, vascular surgery, neurosurgery, electrophysiology procedures, diagnostic ablation of arrhythmias, therapeutic ablation of arrhythmias, endovascular procedures, treatment of injuries to the liver, treatment of the spleen, treatment of the heart, treatment of the lungs, treatment of major blood vessels, non-invasive procedures, invasive procedures, and port-access procedures.
Another aspect of the present invention provides a system for performing a medical procedure. The system includes a transvenous nerve stimulator to inhibit beating of the heart and a cardiac stimulator in communication with the transvenous nerve stimulator to stimulate beating of the heart. The system may also include drug delivery means for delivering at least one drug during the medical procedure such as a spray, a cream, an ointment, a medicament, a pill, a patch, a catheter, a cannula, a needle and syringe, a pump, and an iontophoretic drug delivery device. The transvenous nerve stimulator may stimulate vagus nerve fibers, hypoglossal nerve fibers, phrenic nerve fibers, parasympathetic nerve fibers, and sympathetic nerve fibers, a vagal nerve, a carotid sinus nerve, a fat pad. The transvenous nerve stimulator comprises one or more electrodes such as nerve stimulation electrodes, endotracheal electrodes, endoesophageal electrodes, intravascular electrodes, transcutaneous electrodes, intracutaneous electrodes, balloon-type electrodes, basket-type electrodes, umbrella-type electrodes, tape-type electrodes, suction-type electrodes, screw-type electrodes, barb-type electrodes, bipolar electrodes, monopolar electrodes, metal electrodes, wire electrodes, patch electrodes, cuff electrodes, clip electrodes, needle electrodes and probe electrodes. The cardiac stimulator also comprises one or more electrodes such as cardiac stimulation electrodes, clip electrodes, needle electrodes, probe electrodes, pacing electrodes, epicardial electrodes, patch electrodes, intravascular electrodes, balloon-type electrodes, basket-type electrodes, tape-type electrodes, umbrella-type electrodes, suction-type electrodes, endotracheal electrodes, endoesophageal electrodes, transcutaneous electrodes, intracutaneous electrodes, screw-type electrodes, barb-type electrodes, bipolar electrodes, monopolar electrodes, metal electrodes, wire electrodes and cuff electrodes The system may also include a respiratory controller for controlling respiration.
Another aspect of the present invention provides a method of performing heart surgery. A nerve is stimulated transvenously to reduce the beating of a heart. The heart is operated upon. Stimulation of the nerve is then reduced or stopped. The heart is stimulated to cause beating of the heart. The nerve is then restimulated to re-inhibit beating of the heart and surgery is continued.
Another aspect of the present invention provides a device for performing a medical procedure. The device includes a processor connected to a transvenous nerve stimulation electrode and a cardiac stimulation electrode. The processor processes output from the nerve stimulation electrode and adjusts output from the cardiac stimulation electrode based on output from the nerve stimulation electrode. Stimulation from the nerve stimulation electrode may occur in an inverse relationship to stimulation from the cardiac stimulation electrode.
The foregoing, and other, features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims in equivalence thereof.